Metal treatment furnace



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Sept 23, 1969 C. w. HM 3,468,524

METAL TREATMENT FURNACE Original Filed Aug. l2, 1965 2 Sheets-Sheet 2 fffyf fsw( /rroR//E Ys.

United States Patent Office 3,468,524 Patented Sept. 23, 1969 U.S. Cl. 266-33 6 Claims ABSTRACT OF THE DISCLOSURE Refractory lined furnace housing providing a longitudinal chamber and having an open front end, the housing including a lower section and an upper section supported thereon, freely liftable upwardly therefrom for removal, but interengaged with the lower section by ange means preventing relative lateral and longitudinal movement; an open-mouthed pot rotatably mounted in the chamber with its open mouth adjacent the housing open front end, the pot rotational mounting including a rotatable table carried at the housing other end, the pot being abuttable against the table; and means for tilting the housing and pot together about a transverse horizontal axis adjacent the housing open end.

Summary of the invention This is a continuation ot application Ser. No. 479,251 filed Aug. 12, 1965, now abandoned.

In the preferred embodiment of the invention hereinafter described and illustrated in detail, there is provided a furnace housing including a refractory lining providing an elongated interior having a semi-cylindrical upper wall, and an elongated, generally cylindrical pot rotatably mounted within the interior of the housing and having a closed rear or bottom and an open front end or top. Means are provided for tilting the housing and pot about a transverse horizontal axis near the front end of the furnace between an upper or raised position with the axis of the pot substantially horizontal and a lowered position with the pot axis inclined at 45 or more below the horizontal.

The furnace housing is desirably formed with a removable semi-cylindrical top section to facilitate its disassembly in order to permit periodic repair or replacement of the pot, as may be necessary. The pot proper is made of a strong metal, such as steel, having a melting point substantially higher than that of material to be melted therein such as magnesium. Front and rear pairs of laterally spaced rollers mounted on the lower section of the housing provide rotatable support for the pot, and the end thrust load of the pot when its axis is inclined is taken by abutment of the central portion of the pot bottom against a rotatable table mounted in a thrust bearing carried at the rear end of the housing coaxial with the pot.

The interior of the pot is provided with a number of inwardly projecting blades or the like, desirably formed in a generally helical configuration, a construction which affords substantial advantages in use. Thus, during the period of melting a charge in the pot, and during the subsequent pouring operation, the pot is rotated in such a direction that the helical configuration of the inwardly extending blades tends to urge the contents of the pot downwardly toward the closed bottom, thereby insuring that non-melted portions of the charge are not poured out with the molten magnesium. It will be seen that this feature of the present invention is substantially advantageous in that it permits the melting of pieces of magnesium which may be attached to scraps of material having a higher melting point than magnesium. For example, steel nuts and bolts which may be attached to pieces of magnesium need not be individually removed from the magnesium prior to the melt, thereby avoiding expensive labor costs heretofore needed in separating the magnesium parts from such other pieces of higher melting point material.

Following the pour of molten magnesium, the direction of pot rotation may be reversed while the pot axis is substantially horizontal so that the inwardly projecting helical blades within the pot provide a rapid means of 4 removal and ejection of the non-melted pieces from the open end of the pot, prior to the charging operation for the following heat.

Accordingly, it is a principal object of the present invention to disclose and provide a novel furnace particularly adapted for melting magnesium scrap. Other objects of the invention are to provide, in such a furnace, a rotatable pot having an open top and means for tilting the pot so that the pot axis may assume any desired angular relationship with the horizontal within a wide range; to provide a furnace housing of refractory material made in multiple sections to facilitate disassembly for periodic servicing of the rotatable pot therein; to provide in such a furnace a pot having generally helically disposed blades projecting inwardly 4from the cylindrical side wall of the pot; and for other and additional objects and purposes as will become clear from a study of the following description of a preferred embodiment of the invention, taken in connection with the accompanying drawings, in which:

FIG. 1 is a vertical sectional view of one embodiment of a furnace in accordance with the present invention, the axis of the pot being shown in its horizontal position.

FIG. 2 is a rear end view of the furnace taken on the arrows II-*ll of FIG. l.

FIG. 3 is a fragmentary sectional view taken on the arrows III-lll of FIG. 1.

FIG. 4 is a front end view of the furnace, taken on the arrows IV-IV of FIG. l.

FIG. 5 is a view similar to FIG. l, but showing the furnace with the pot axis inclined approximately 45 below the horizontal, and with a charge within the pot being melted.

FlG. 6 is a fragmentary sectional view taken on the arrows VI-VI of FIG. 5.

The furnace of the present invention as seen in FIGS. 1 and 2 is shown raised out of the pit into which it may be lowered during a melt. The pit includes a bottom 10, front and rear walls 11 and 12 respectively, and side walls 13 and 14. Within the pit there is a supporting substructure indicated generally at 15 and including a front vertical wall 16 and a horizontally extending bottom plate 17 resting upon the pit floor 10. The substructure includes also side walls 18 and 19, carrying at their upper ends reinforcing members 20 and 21 respectively, which at their upper ends provide journals 22 and 23 for supporting the front end of the present furnace for pivotal rotation about a horizontal axis, as will be generally understood by a comparison of FIGS. l and 5. A xed support rest indicated generally at 25 provides a limit for downward movement of the furnace.

The furnace housing in accordance with the present invention is made up of a lower section and an upper section, the latter being readily removable from the lower section by a crane or other hoisting equipment. The upper section is generally semi-cylindrical in shape, and the sections desirably mate along the plane passing through the axis of rotation of the pot of the furnace. Thus, with particular reference to FIG. l, the lower section indicated generally at includes a generally rectangular flat base plate 32 made of strong metal such as steel or the like,

desirably reinforced by laterally extending members 34, and provided with a refractory lining 36 above the base plate. At its front end, base 30 is provided with a transversely extending support shaft 38, which is journaled for pivotal rotation in journals 22, 23 previously referred to and carried by the support substructure 15. Spaced from the support shaft 38, and desirably close to the rear end of the base 30, there are lugs 40 projecting downwardly from the base plate 32 and carrying a pivot pin 42. Means are provided for raising the furnace from its lowered position of FIG. to its upper position of FIG. l, such means being here indicated generally at 46 and including a hydraulically actuated ram whose extensible upper piston 48 is pivotally attached to the pivot pin 42 carried by base 30. The elevating means including ram 46 is pivotally mounted at its lower end 50 on suitable lugs 52 extending upwardly from plate 17 of substructure 15. It is to be understood that elevating means 46 here illustrated is actuated through suitable conduit means from a source of pressurized Huid, such details being omitted since they are well known in the art and form no part of the presen invention. i*

The upper section of the furnace housing is indicated generally at 60, and is generally semi-cylindrical in shape. The section includes an outer steel casing 62 carrying within it a simi-cylindrical refractory lining 64, the casing 62 being also provided with one or more lifting eyes 66 projecting upwardly therefrom, by which the upper section may be removed with a crane, hoist or the like when desired. One or more stack openings 68 may be formed through the upper part of section 60 to permit escape of combustion products from the combustion chamber formed within the two sections of the furnace housing. In order to further define the combustion chamber, there are desirably provided at the ends of the upper section 60 a pair of semi-annular refractory members 70 and 71, which mate with similar semi-annular members 72 and 73 carried by the lower section 30.

Base section 30 of the furnace housing also includes means for rotatably supporting the pot of the present invention, such means being here shown as including a pair of laterally spaced rear support wheels 76, 77 (see FIG. 2) and a pair of laterally spaced front support wheels 78 and 79 (see FIG. 4). Each of these support wheels is rotatably mounted in suitable brackets 80 mounted on the lower section 30. The wheels or rollers 76, 77, 78 and 79 provide rolling support for a longitudinally spaced pair of annular metal tires carried by the pot, as will be later described in detail.

The pot of the present furnance is indicated generally at 90 and is cylindrical in shape, having a closed bottom and an open top. Thus, with further reference to FIGS. 1 and 5, pot 90 includes cylindrical side wall 92 terminating leftwardly as seen in the drawings in a closed bottom indicated generally at 94. In order to protect the driving motor and other mechanism from the effects of excess heat, bottom 94 is desirably provided with a layer of refractory material 96 between a pair of circular steel plates 97 and 9S. The lower of these plates, 97, is provided with a rearwardly extending central boss 100l (see FIG. 3), whose rear circular face 102 is in abuting supportable contact with a freely rotatable table 104 for end thrust support during rotation of the pot, as will be later described in detail. The pot is supported for rotation by metal tires 106 and 108 at the rear and front ends respectively of the pot, the outer peripheries of the tires resting upon the support rollers 76, 77 at the rear end and 78 and 79 at the front end of the furnace housing.

Means are provided within the pot 90 for urging the contents of the pot longitudinally thereof during rotation of the pot. In the present embodiment of the invention such means include inwardly projecting blades 110, which are desirably disposed to form a continuous or substantially continuous helix within the pot. The helix terminates close to the open upper end 112 of the pot.

Means are carried by the furnace housing, and particularly by the lower section 30 thereof, for rotatably driving the pot during opertion. As best seen in FIG. 2, such driving means include a motor coupled through shaft means 122 to a gear box 124 whose output power is supplied to a drive gear 126 through intermediate gears 127 and 128 and chain 129. Pot 90 is provided at its rear end with a ring gear indicated generally at 130, meshing with the drive gear 126, the latter being desirably disposed below the rotational axis of pot 90 to facilitate removal and replacement of pot 90 when necessary,

The drive means for the pot, including motor 120, gear box 124 and drive gear 126, are carried on a support frame indicated generally at and extending rearwardly from the main portion of the lower section 30. Also mounted upon the frame extension 140 is a pillow block indicated generally at 142 and best seen in detail in FIG.

3. Within block 142 there is rotatably mounted a shaft Y 144 rotatably supported by thrust bearing 146, the shaft 144 having fixed thereto at its right end, as seen in FIG. 3, the enlarged table 104 previously referred to. The outer face of the table 104 is in abutting supporting engagement with circular face 102, for supporting the longitudinal thrust load of the pot when the axis of the pot is below the horizontal as in FIG. 5 and other positions intermediate between the positions of FIGS. 1 and 5.

One or more burner means are provided for externally heating pot 90 within the furnace housing. With particular reference to FIG. 6, one such burner is indicated generally at 150, and is supplied with gas and air through conduits 151 and 152 from suitable sources not shown. The heated gases from the burner are indicated generally at 153, impinging the side wall 92 of pot 90. Desirably, another similar burner is provided on the opposite side of the furnace housing, being indicated generally at 154 (see FIG. 4). It will be noted that the burners 150 and 154 are disposed substantially below the center line of the furnace housing and pot, for most eicient distribution of the heated gases therefrom to heat the pot and its contents during operation.

Also seen in FIG. 6 is the engagement between the upper and lower sections of the furnace housing. Thus the lower section includes a pair of laterally spaced vertical side walls extending upwardly from the fioor formed by plate 32 and refractory lining 36, one of the side walls being indicated generally at 155 and including a steel plate 156 and refractory lining 157. Wall 155 terminates upwardly in a flat top 158, desirably generally coplanar with the axis of pot 90, and the bottom face 159 of upper section 60 rests thereon. Means are provided for retaining the two sections of the furnace housing in assembled relationship during operation, and particularly during the tilting movement between FIGS. l and 5, such means desirably permitting ready assembly and disassembly of the two furnace housing sections. A preferred form of such means includes a strong metal strap carried by each of the side walls of the lower section 30 of the furnace housing, the width of the straps being such as to project above the lower section. Such straps are indicated generally at 160 and 162. Each of the straps is fixed to its respective side wall by suitable means such as weld 164. It will be seen that the portions of the straps 160 and 162 which project above the side walls of base section 30 constitute in effect flanges for receiving therebetween the lowermost portions of the upper section 60 of the furnace housing, and providing lateral alignment between the two mating sections of the housing. Longitudinal alignment of the two sections is desirably provided by inturned ends of the two straps 160 and 162. Thus, strap 160 includes inturned end portions and 166 at its rear and front ends respectively, while strap 162 includes inturned end portions 167 and 168 at its rear and front ends respectively. It will thus be seen that the inturned end portions, and particularly end portions 165 and 167 at the rear end of the furnace housing, prevent the upper section 60 from moving longitudinally relative to the lower section 30 of the furnace housing when the furnace is in the position of FIG. 5. Although the position of the furnace as shown in FIG. 1 is intended to be its uppermost position, nevertheless, if the furnace is raised above that of FIG. 1, the inturned end portions 166 and 168 at the front end of the housing will serve to prevent longitudinal movement of the furnace housing upper section 60.

Access means may be provided into the rear end of the combustion chamber of the furnace housing. In FIG. 1 there is indicated generally at 170 a removable closure for an access opening at the rear or lower end of the furnace. This permits operating personnel to periodically remove iron oxide and similar material which may fall from the outside wall of the pot during operation. It is important that such material be removed promptly, to prevent the possibility of an explosion if such iron compounds come into contact with molten magnesium.

Means may also be provided in accordance with the present invention for burning exhaust gas given 01T from the open end of the pot during operation. As seen in FIGS. 4 and 5, a burner indicated generally at 176 and provided with gas and air through conduits 177 and 178, may provide a flame 179. This is particularly desirable, and may indeed be required, in areas where air pollution is a problem.

A typical furnace in accordance with the present invention may include a pot having a diameter of approximately our feet and a length of approximately eight feet, permitting a melt of approximately 7,000 pounds of magnesium scrap during each heat. It will be understood that each such heat may also include pieces of material having a substantially higher melting point than magnesium. For example, as seen in FIG. 5, the melt indicated generaly at 180 may include one or more pieces 182 and 184 of steel or similar material. During the heating operation, as well as the subsequent pouring operation, the rotation of the pot is such that the etect of the inwardly extending 'blades 110 is to urge such pieces, as well as the melt generally, toward the bottom or rear end of the pot. Then, following the pour of molten magnesium, the direction of rotation of the pot may be reversed, either by mechanical means in gear box 124 or by reversing the direction of rotation of motor 120 by electrical means, so that the pieces of scrap steel such as 182, 184, as well as sludge and the like, will be moved toward the open end of the pot and expelled therefrom.

The present furnace provides for externally heating the charge in the pot, thereby minimizing oxidation as is particularly important in melting magnesium. The pot wears evenly during use and thus lasts much longer than ixed pots usually used for melting magnesium. The split construction of the furnace housing, in conjunction with the pot support means above described, permits very rapid removal of the pot when repair or replacement is necessary.

Although a particular embodiment of the invention has been illustratively described and shown hereinabove, nevertheless it will be understood that the invention is subject to many modifications and changes from such illustrative embodiment. All such modifications and changes not departing from the spirit of the invention are intended to be embraced within the scope of the appended claims.

I claim:

1. A metal treatment furnace including a hollow housing providing a longitudinal chamber open at its front end, a cylindrical pot rotatably mounted in the chamber and having a closed rear end and an open mouth adjacent the chamber open end, means for heating the chamber, and means for tilting the housing and pot between an upper position with the pot axis substantially horizontal and a lower position with the axis of the pot inclined downwardly from its open mouth,

characterized in that the housing includes a lower section and an upper section supported thereon along a plane of juncture, and provided with means for preventing relative lateral and longitudinal movement between the sections, including members carried by one of said sections which project beyond the plane of juncture and which, during assembly of the sections, slidably interengage with the other section and after assembly, are in abuttable relation with said other section.

2. The invention as defined in claim 1 including a table carried by the rear end of the housing lower section and rotatable coaxially with the pot, the pot rear endl being in abuttable supported engagement with the tab e.

3. The invention as dened n claim 2 including means for rotatably mounting the pot in the chamber comprising said table and front and rear pairs of laterally spaced rollers carried by the housing lower section.

4. The invention as defined in claim 1 wherein the pot axis is substantially coincident with the plane of juncture.

.5. The invention as delined in claim 1 wherein the .projecting portions of said members constitute flanges defining the lateral and longitudinal extent of the other housing adjacent the plane of juncture.

6. The invention as defined in claim 5 wherein said members are carried by the housing lower section and the anges engage the lowermost portions of the housing upper section when the sections are in assembled relation.

References Cited UNITED STATES PATENTS 2,158,689 5/ 1939 Buchanan 266-18 2,481,699 9/ 1949 Stroman 266-33 2,590,843 4/ 1952 Cremer 266-33 3,144,245 8/ 1964 Martin 266-33 3,193,273 7/ 1965 Miller et al 266-37 3,272,489 9/ 1966 Heyer et al 266-4 I. SPENCER OVERHOLSER, Primary Examiner EUGENE MAR, Assistant Examiner U.S. Cl. X.R. 266-18, 36, 38 

